The present invention relates to an array for the transmission of electrical energy or signals, respectively between a base station and several external units adapted to be coupled without contact to various positions on the base station.
Mechanical plug-and-socket connectors are frequently employed for contacting frequently mobile means. Such mechanical contact systems are commercially available in a very wide variety of types and models. As a rule, a comparatively high expenditure is required in order to protect the contact systems from influences from the environment. Here, aspects such as touch-preventing guards, protection from penetrating liquids such as water, oil or even moisture play an important role.
Particularly high demands prevail in areas protected from explosion. In order to satisfy such requirements it is necessary to encapsulate the contact means in a complex and high-cost manner. As a consequence, the structure is substantially changed whilst handling is rendered more difficult. Specifically with frequent plugging and unplugging cycles, such plug-and-socket connectors present serious disadvantages.
Contact-less connecting systems constitute a substantial improvement here. Non-contacting transmission systems, which are based on inductive coupling, are known in manifold configurations. One example of a system based on inductive coupling is described in the German Patent 197 01 357 A1. It avoids the principal disadvantage of contacting systems but it entails comparatively high production costs. There, a separate AC voltage generator and, on the opposite side, a corresponding rectifier are necessary for each transmission system. This results in intolerable high costs particularly in installations with a high number of contacting means.
Further systems are known from the German Patent DE 44 36 592 C2, the German Patent DE 196 48 682 A1 or the German Patent DE 197 35 685 A1.
The invention is based on the problem of proposing an array for contact-less transmission, which can be realised at low costs specifically in a high number of transmission sites.
One inventive solution to this problem is defined in Patent Claim 1. Improvements of the invention are the subject matters of the dependent claims.
This inventive array is composed of one respective switching controller per contact site.
The inventive array consists particularly of a fixed-cycle power supply for potential-free transmission of energy, with the potential-isolating elements being designed as contact-less transmission means. Potential-isolating power supply units in correspondence with prior art are provided, as a rule, with a power switching stage on the primary side, which generates an alternating voltage. This voltage is then transmitted to the secondary side by means of a potential-isolating transformer. There the output parameters are rectified and measured. A feedback signal is generated from these output parameters, in its turn, which is transmitted in a potential-free manner to the primary side for control of the power generator. Such arrays are provided with two paths in which potential isolation is required. On the one hand, this is the path of the power flow from the primary side to the secondary side, and, on the other hand, this is the feedback path for control of a constant output parameter from the secondary side to the primary side. In an inventive contact-less transmission means, now both potential-isolating paths are replaced by non-contacting transmission elements. In the case of the power path, the potential-isolating transformerxe2x80x94which is provided anyhowxe2x80x94is split into two parts whereof each contains a winding and a ferrite or iron core, respectively, for controlling the magnetic flux. It is now possible to separate the primary and the secondary sides from each other and to re-assemble them in a simple manner. In the case of a feedback path, with potential isolation, from the secondary side to the primary side the transmission is preferably realised via a capacitive coupler element. As an alternative, this information may also be transmitted with an inductive or optical technique. Preferred capacitive coupler elements are the subject matter of the German Patent Application DE 197 00 110 A1.
In a particularly expedient embodiment of the invention, the circuit is designed as a resonance transducer for the transmission of energy. Such transducers present essential advantages here. Transformers that can be split and where the primary and secondary sides may be separated from each other display a variable leakage inductance due to the mostly varying air gap between the primary and secondary sides. Due to its impedance, this leakage inductance restricts the flow of current in the transformer. When this leakage inductance is compensated by a corresponding capacitance an optionally low impedance can be achieved in the case of resonance. By virtue of their utilising this effect, resonance transducers are able to operate with a substantially higher efficiency here.
Another embodiment of the invention consists in the aspect that these capacitive coupler elements are disposed in the immediate coupling range of the inductive coupler elements. Such an arrangement permits a substantially space-saving structure because additional space is not required for the capacitive coupling means. Such an arrangement of the capacitive coupler elements in the magnetic field of the inductive transmission means allows for independent transmission of both signals.
This is possible without any problems in the inventive array because electrical fields and magnetic fields do not take an influence on each other.
When in another expedient design of the invention the capacitive coupling means is designed here in the form of a pc board it offers additional mechanical protection for the inductive coupling means. In distinction from the array represented in the laid-open German Patent Application DE 4125145, the inventive array provides for a complete cover of the inductive coupler element.